It was therefore an object of the present invention to provide a process of the type specified at the outset, in which no H-functional starter substances need be initially charged in the reactor. Furthermore, the process was to enable the production of a product having a high content of incorporated CO2 in the resulting polyetherester carbonate polyol.
The object was achieved by a process for preparing polyether ester carbonate polyols by adding at least one alkylene oxide, at least one cyclic anhydride and carbon dioxide onto one or more H-functional starter substances in the presence of a double metal cyanide catalyst (“DMC catalyst” for short), wherein the process is characterized in that                (α) a suspension medium containing no H-functional groups is initially charged in a reactor and        (γ) one or more H-functional starter substances is metered continuously into the reactor during the reaction and the metered addition of one or more alkylene oxides, the cyclic anhydride and optionally the carbon dioxide is effected simultaneously or sequentially.        